GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 239 



Frequently it is difficult to decide whether or no to apply the desig- 

 nation "coral reef" to richly coralliferous deposits that are obviously 

 bedded. However, I am applying it wherever corals of reef facies 

 seem sufficiently abundant to have formed appreciable rugosities 

 on the sea bottom, although the deposits are bedded. 



Reefs predominatly formed by calcareous algae should be desig- 

 nated "nullipore" or "Lithothamnium reefs." However, where 

 the proportion of these organisms to corals is so nearly the same that 

 only exact computation will decide between the two, such a reef 

 may be designated "coral." The expression "reef coral" will be 

 applied to corals of the facies usual in reefs; and "coralliferous 

 limestone" or "coralliferous beds" will be applied where corals 

 are present, although they may be rare. Rock predominantly com- 

 posed of the shells of mollusks, of the tests of foraminifera and 

 Bryozoa, and of chemically precipitated calcium carbonate are. ex- 

 cluded from the category "coral reefs." 



The restricted use of the term "coral reef" in this paper will prob- 

 ably be disapproved by a considerable number of nnvestigators,but 

 in my opinion it is essential to clear thinking. Limestones are 

 initially formed by one of two processes, namely, (1) through chem- 

 ical precipitation either by inorganic or organic agencies that lead 

 to supersaturation of water with reference to calcium carbonate 

 (CaC0 3 ), (2) through the activity of organisms that cause the pre- 

 cipitation of calcium carbonate (CaC0 3 ) in contact with their soft 

 tissues. Corals belong to a group of organisms that secrete calcium 

 carbonate (CaC0 3 ), that is, cause the precipitation of calcium car- 

 bonate (CaC0 3 ) in contact with their soft tissues. Every kind of 

 shoal-water calcium-carbonate deposit has been called "coral rock": 

 the molluscan-shell sands of the Bermudas, the chemically precip- 

 Fitated calcium carbonate of the oolites of Florida and the Bahamas, 

 and limestones composed of the remains of Foraminifera and Bryozoa. 

 The terms coral sand and coral mud have been applied to bottom- 

 deposits in which there is no coral. To apply the term "coral rock" 

 or "coral-reef rock" to all the kinds of limestones indicated would at 

 the present time, in my opinion, be willful mental obfuscation. 

 The study of the origin of limestones and the classification of lime- 

 stones according to the source of their ingredients constitute a 

 scientific problem of great geologic importance, and I believe it a 

 scientific duty to break away from a usage that in most instances 

 concealed scientific fact. 



The importance of the distinction between "reef" and the mate- 

 rial lying between a "reef" and the shore is particularly discussed 

 on page 249. 



